What’s Next for WAAS?

In 2007, the Wide Area Augmentation System (WAAS) expanded its coverage, transitioned 

to new GEO satellites, and continued making system enhancements to keep the WAAS 

momentum moving forward. Additionally, over 300 new LPVs were published, bringing the 

total number of LPVs at the end of 2007 to nearly 1,000. Equipage also continued to 

steadily increase as more users embraced the benefits that WAAS provides. With all this 

accomplished, one might ask, “What’s next for WAAS?” The answer is “even more”. 

The WAAS project consists of four phases. Phase I was completed in 2003 with the initial 

commissioning of the WAAS. Phase II is currently underway and will be completed this 

year. At that point, the FAA will embark upon the two final phases of WAAS. Phase III, 

which will begin in 2009, is referred to as the “Full LPV-200 Performance” phase. This 

phase will include modifications and enhancements, including technology refresh. During 

this time, the FAA will be involved in a series of operational initiatives to extend the benefits 

of the existing service. In 

particular, emphasis will be 

placed on the production of 

WAAS approach procedures 

that support minimums as low 

as 200’. The FAA has a jump 

on this initiative as there are 

already 12 published WAAS 

LPVs that go down to 200’. 

Phase IV, currently expected to 

start in 2014, is referred to as 

“Dual Frequency Operations”. 

This final phase will focus on 

making enhancements to 

WAAS to take full advantage of 

future dual frequency GPS. As 

such, FAA has aligned its 

WAAS Phase IV project 

schedule with that of the DoD’s 

GPS modernization program. 

After Phase IV is complete, the 

FAA will continue to support 

single frequency users, but for those interested in dual frequency, there will be added 

benefit. Availability and continuity during severe solar activity will be greatly improved. 

Additionally, this capability will provide additional protection against GPS interference. 

Phase IV is scheduled for completion in 2028. 

Throughout this development, the FAA will continue to work with the International Civil 

Aviation Organization (ICAO) and other international satellite based augmentation system 

(SBAS) service providers to ensure interoperability and to help extend the benefits and 

coverage of the worldwide SBAS network. Additionally, WAAS will be a cornerstone of the 

FAA’s Next Generation (NextGen) Air Transportation System, providing a robust navigation 

In this issue:

What’s Next for WAAS?...............1 

FAA to Publish New Line of Minima 

for WAAS on RNAV (GPS) 

Instrument Approach Charts.........2 

LPV Watch: WAAS-Based 

Approach Procedures Surpass 

1,000.............................................3 

WAAS Avionics Update................3 

2008 - An Exciting Year for 

LAAS............................................3 

GNSS in the News........................4 

GNSS on the Road........................5 

Subscription Service for GPS/ 

WAAS Approaches Web Page 

Takes Off......................................5 

The SATNAV News is produced by the 

Navigation Services (ATO-W) branch of 

the Federal Aviation Administration. This 

newsletter provides information on the Wide 

Area Augmentation System (WAAS) and 

the Local Area Augmentation System 

(LAAS), and initiatives associated with the 

implementation of satellite navigation into 

the National Airspace System (NAS). 

Federal Aviation Administration 

800 Independence Avenue, SW 

Washington, DC 20591 

http://gps.faa.gov
2

source for ADS-B applications and providing area navigation 

services for Required Navigation Performance (RNP) and Area 

Navigation (RNAV) operations. WAAS has already matured 

into a critical navigation services component for current and 

future users, but there is much more to come. Stay tuned. 

 - Mary Ann Davis, FAA ATO-W/GPS TAC

FAA to Publish New Line of Minima for 

WAAS on RNAV (GPS) Instrument 

Approach Charts 

Soon, some RNAV (GPS) instrument approach procedures 

(IAPs) will have a new line of minima. Labeled on the charts 

as ‘LP’, localizer performance minima will allow operators with 

appropriately-certified Wide Area Augmentation System 

(WAAS) navigation systems to fly instrument approaches in 

potentially lower weather conditions to runways that do not 

qualify for localizer performance with vertical guidance (LPV) 

minima. These new approaches are the result of new terminal 

instrument procedures (TERPS) criteria recently approved by 

the FAA and will benefit both fixed wing and rotary wing for 

instrument flight rules (IFR) operations. 

For pilots landing at airports in less than optimal weather 

conditions, IAPs are the key to guiding the pilot through clouds 

and low visibility to a point where the runway can be seen and 

the approach and landing completed visually. A combination 

of navigation systems, aircraft capabilities, and instrument 

approach design criteria determine how low the minima for an 

approach will be. 

An LPV procedure has often been referred to as the satellite 

navigation equivalent of the Instrument Landing System (ILS) 

as both LPVs and ILSs provide vertical guidance. As the name 

implies, an LP approach is the equivalent of a localizer-only 

approach. Like many localizer-only approaches that serve 

runway ends with obstacles that prevent use of an ILS, LP 

approaches are intended to utilize the benefits of WAAS in 

locations where a vertically-guided LPV approach is not feasible 

due to obstacles or terrain. 

Technically, LP differs from existing LNAV (lateral navigation) 

minima by allowing approach developers to use a smaller 

obstacle evaluation area based on localizer-like angular 

guidance and the much smaller integrity limits of WAAS. 

Obstacles offset from the approach course that raise the 

minimum descent altitude (MDA) for an LNAV may not 

necessarily affect the MDA for LP. This results in potentially 

lower minimums, and in the case of low instrument 

meteorological conditions, the difference between landing and 

diverting to another airport. 

There are minimal operational differences between an LP and 

LNAV approach. On an LNAV approach, full scale deflection 

is ±0.3 nautical miles (NM) at the final approach fix (FAF) and 

continues at this scaling until the runway threshold. An LP 

procedure is designed similar to a localizer approach with the 

course narrowing from approximately ±1400 feet at the FAF to 

±350 feet at the threshold. The LP procedure is not verticallyguided so the minimum is depicted as an MDA, rather than a 

decision altitude (DA) in the case of an LPV. 

The publication of LP procedures will not have any effect on 

the continuing development of LPV approaches. The FAA has 

published over 1,000 LPV approaches to date and has 

committed to publishing an LPV procedure to every runway in 

the National Airspace System (NAS) that will qualify. As a 

result, there will never be a need for both LPV and LP minima 

on the same instrument approach chart—a good thing 

considering LP certified avionics cannot store both LP and 

LPV procedures for the same approach in their database. 

While the criteria for LP procedures have been approved, it will 

likely be the fourth quarter of 2008 before LP lines of minima 

begin to appear on charts. This takes into consideration the 

time required for training of procedure development specialists, 

configuration of procedure development tools, and normal 

timeline for development of a procedure. Further, while WAAS 

avionics certified under TSO-C145B or TSO-C146B may be 

configured for LP, avionics certified under prior technical service 

orders (TSO) may require updates in order to properly depict 

LP procedures. The flight manual for your avionics should 

indicate whether your WAAS receiver is LP ready. 

While it is too soon to estimate how many LP procedures will 

be published, LP is further proof that the FAA is committed to 

utilizing satellite-based navigation to increase safety while 

providing the lowest minima and IFR accessibility to thousands 

of airports in the NAS. 

- Brad Zeigler, FAA ATO-W/GPS TAC
3

LPV Watch: WAAS-Based Approach 

Procedures Surpass 1,000 

February 14, 2008 marked a new milestone for the FAA Global 

Navigation Satellite System (GNSS) Program. As of this latest 

charting cycle, there were more than 1,000 instrument approach 

procedures with localizer performance with vertical guidance 

(LPV) minima. 

This charting cycle yielded 33 additional procedures for a total 

of 1,028 LPV procedures. More than half (58%) of all LPV 

procedures are to runways without an existing instrument 

landing system (ILS). 

The LPV utilizes WAAS to provide vertical guidance for satellitebased approaches. The FAA began publishing GPS 

approaches in 1994 and has published 4,411 GPS and RNAV 

(GPS) procedures to date. In 2003 the FAA published the first 

RNAV (GPS) procedure with LPV minima. Today, 23% of all 

published satellite-based approaches include LPV. 

1,275 RNAV (GPS) procedures include lateral/vertical 

navigation (LNAV/VNAV) minima. Originally intended for 

aircraft with barometric vertical guidance, WAAS users with 

avionics certified for LPV can also fly to LNAV/VNAV minima. 

Between LPV and LNAV/VNAV procedures that do not yet 

have LPV minima, 33% of all RNAV (GPS) procedures can be 

flown with published vertical guidance. 

Satellite-based procedures represent about 42% of the 

approximately 10,500 instrument approach procedures 

maintained by the FAA. As the agency continues to publish 

new RNAV (GPS) procedures while decommissioning littleused ground-based procedures such as NDB, that percentage 

will steadily increase. 

A listing of current airports and runways served by LPVs can

be found on our website. To access this information, go to

http://gps.faa.gov and select the GPS/

WAAS Approaches button from bottom of

the front page.

 - Brad Zeigler, FAA ATO-W/GPS TAC

WAAS Avionics Update 

Garmin recently announced that they will no longer be manufacturing the venerable GNS-480. They will however continue 

to support the unit and work toward the removal of the IFR 

GPS operational “primary means of navigation” limitation. This 

limitation has already been removed from the GNS 400W and 

500W avionics family under Garmin’s Software Service Bulletin No. 0740 Rev. A, published November 29, 2007. This bulletin describes the process for upgrading the 400W/500W unit’s 

main software to version 3.0 and upgrading the GPS software 

to version 3.0. This software also includes some 15 new features and capabilities. 

Universal Avionics has recently announced that development 

of their single WAAS flight management system (FMS) capability is progressing on schedule with expected certification 

early in the second quarter of 2008. These single WAAS 

FMSs will be available in the UNS-1E, UNS-1Esp, UNS-1F 

and UNS-1L models and will also include Localizer Performance (LP) approach capability. (For more information on LP

capability, please see “FAA to Publish New Line of Minima for

WAAS on RNAV (GPS) Instrument Approach Charts” on page

2.) The single FMS installation will be particularly applicable 

to helicopter and medium-size transport category airplanes 

where pedestal space and weight are major considerations. 

Universal’s WAAS products are also seeing many and varied 

airframe applications both here in the US and Canada. Canadian carrier First Air has equipped Boeing 727-200 series aircraft with UNS-1Fw FMSs while ARC Avionics of Miami, Florida 

is working toward the integration of a UNS-1Fw FMS in Boeing 

737-200 aircraft. Cessna Aircraft is also progressing toward 

supplemental type certificate (STC) development in the Citation XLS series with UNS-1Espw FMSs. 

I’d like to thank those of you who responded to our last update

with both comments and questions. Don’t hesitate to send a

note (thomas.ctr.salat@faa.gov) to either ask a question, or

provide feedback or suggestions.

 - Tom Salat, FAA ATO-W/GPS TAC

2008 - An Exciting Year for LAAS 

2008 is expected to be a big year for LAAS. By the end of 

2008, the first Category (CAT) I LAAS is expected to be certified 

in compliance with the International Civil Aviation Organization’s 

(ICAO) Standards and Recommended Practices (SARPS). 

This accomplishment will be the much anticipated result of 

many years of research and development, international 

cooperation, and strong coordination between government and 

industry stakeholders. At present, the LAAS program is 
4

finishing work to address LAAS safety requirements and 

complete a hazardously misleading information (HMI) analysis, 

expected to be complete by March. The next step will be 

system design approval. Upon the completion of system design 

approval, the way will be clear for certification - also referred to 

as Part 171 non-Federal approval. 

Simultaneously with the CAT I LAAS work, the FAA has also 

continued work toward a CAT II/III LAAS capability. This work 

includes coordination with RTCA, ICAO, and other industry 

partners. RTCA is currently reviewing and modifying a joint 

FAA/Boeing proposal on CAT II/III requirement allocation. 

Concurrently, ICAO is reviewing and modifying the SARPS 

proposal. In conjunction with RTCA and ICAO reviews, the 

FAA Navigation Services group is updating the draft non-Federal 

ground facility specification. The next major milestone for 

LAAS CAT II/III is expected in May 2008 when the Category I 

non-Federal ground system is delivered. The CAT I ground 

system will provide a platform to begin validating CAT II/III 

concepts. In September of 2008, the non-Federal ground 

specification will be updated to reflect recommended changes 

from RTCA and ICAO. 

In the meantime, international interest in LAAS, or GBAS 

(Ground Based Augmentation System), as the system is 

referred to internationally, remains high. The International 

GBAS Working Group (IGWG) continues to meet regularly. 

The next meeting is scheduled in Brazil in April and will be 

hosted by DECEA Brazil. This international working group 

has had strong impact on the proliferation of LAAS technology. 

With the GBAS technology moving from the development stage 

to the implementation stage, new participants - especially, 

commercial airlines - have joined the working group to monitor 

the progress and to provide information about their operations 

and equipage plans. As a part of those plans, new generation 

Airbus and Boeing aircraft will be GBAS-capable, including 

the new Boeing Dreamliner which includes GBAS capability 

as standard equipment. 

More and more countries continue to approach the FAA to 

learn about the development and implementation of LAAS. In 

the last quarter, the FAA GNSS Program Office has hosted 

visitors from both Chile and Japan. These international 

delegations visited the LAAS test prototype in Memphis and 

also had the opportunity to meet with GNSS team members 

at FAA headquarters. The certification work underway in 

Memphis also has an international connection. The FAA’s 

work in Memphis is complemented by that of Air Services 

Australia in Sydney. The FAA and Australia are working 

together under an international agreement to achieve LAAS/ 

GBAS certification as soon as possible to the delight of many 

LAAS enthusiasts. This international cooperation will be the 

key to achieving the most expeditious path to Part 171 nonFederal approval. 

In future editions of the SATNAV News, we will bring you 

updates on all these activities as the countdown to LAAS 

certification gains increasing momentum. 

 - Mary Ann Davis/Dieter Guenter, FAA ATO-W / GPS TAC

GNSS in the News 

Recently, a few articles related to the FAA’s GNSS program 

have appeared in aviation trade magazines. Here are a couple 

that we came across in case you are interested in checking 

them out. 

Y “WAAS Expands” by David Hughes. (December 24/31, 

2007). Aviation Week and Space Technology, p. 34. 

The web link is: http://www.aviationweek.com/search/

AvnowSearchResult.do?reference=xml/awst_xml/2007/12/

24/AW_12_24_2007_p34-20425.xml (Access may be

limited to Aviation Week subscribers.)

Y “WAAS-enabled GPS systems support precise navigation” 

by Barry Rosenberg. (January 2008). Avionics Magazine, pp. 

43-46. 

The web link is:

http://www.aviationtoday.com/av/categories/bga/18080.html.

Building momentum for 2008, LAAS closed out 2007 with a

successful flight trial in Malaga, Spain. The flight trial was

conducted with an Airbus 320 aircraft against a Honeywell SLS3000 ground station, identical to the one in Memphis. FAA and

Spain’s Aeropuertos Españoles y Navegación Aérea (AENA) are

working closely on implementation of GBAS/LAAS under a

cooperative agreement for research and development.
5

GNSS on the Road 

As a part of outreach, representatives of the FAA GNSS 

Program Office will be participating in several of our 

stakeholders’ conferences this spring. If you plan to attend 

any of these events, please stop by and say “hello”. 

Events attended earlier this year:

Northwest Aviation Conference

Puyallup, WA 

February 23 - 24, 2008 

Helicopter Association International (HAI) - HELI-EXPO

Houston, TX 

February 24-26, 2008 

2008 ACC/AAAE Airport Planning, Design and

Construction Symposium

Denver, CO 

February 27-29, 2008 

Upcoming events:

Experimental Aircraft Association (EAA)

Sun ‘N Fun 

Lakeland, FL 

April 8-13, 2008 

Texas Aviation Conference

Austin, TX 

April 15-17, 2008 

Alaska State Aviation and Trade Show and Conference

Anchorage, AK 

May 3-4, 2008 

RAA Annual Convention

Indianapolis, IN 

May 5-8, 2008 

FAA Western Pacific Regional Airports Conference

Los Angeles, CA 

May 5-8, 2008 

Subscription Service for GPS/WAAS 

Approaches Web Page Takes Off 

In early October, we began offering an option to our website 

visitors to subscribe to a few of our web pages, to include the 

GPS/WAAS Approaches page. As of late January, in just a 

few short months, over 700 of you have signed up to receive 

e-mail notifications when the GPS/WAAS approaches 

information is updated. We are encouraged by this interest 

and hope you are finding the information posted helpful. 

If you haven’t yet signed up for this service, but are interested, 

you can sign up by one of two ways. 

Y Visit http://gps.faa.gov and select the GPS/WAAS 

Approaches button at the bottom of the page. From the GPS/ 

WAAS Approaches page, simply click on the “Subscribe to 

this page” link in the right margin and follow the online 

instructions from there. Or... 

Y Visit http://www.faa.gov/help/subscribe/. After a quick 

process (which requires no personal information other than 

the e-mail address to which you would like the notifications 

sent), select “GPS/WAAS Approaches” from the list of options. 

After you have completed either process, you will receive an 

e-mail notification confirming that you have been added to the 

service. 

- Mary Ann Davis, FAA ATO-W / GPS TAC

SATNAV News is posted on our website. You may request to be notified by e-mail when new editions are posted by 

entering your e-mail address at http://www.faa.gov/help/subscribe/ and selecting SATNAV News from the list of options. 

If you have any questions on the e-mail registration process, ideas for future articles, or general feedback on the 

newsletter, please contact Mary Ann Davis at maryann.ctr.davis@faa.gov.